Ternary Layered Double Hydroxides Research Articles

Application of cobalt-cerium-iron ternary layered double hydroxide for extraction of perfluorooctane sulfonate followed by HPLC-MS/MS analysis

Herein, Ce-doped CoFe layered double hydroxide (LDH), noted as CoCeFe ternary LDH, was prepared using the co-precipitation route. Prosperous synthesis of CoFe LDH and successful partial replacement of iron cations with cerium cations in CoCeFe ternary LDH were confirmed by X-ray diffraction patterns, energy-dispersive X-ray spectroscopy, and elemental dot-mapping images. Nanosheet morphology was recognized for both CoFe LDH and CoCeFe ternary LDH from scanning electron microscopy and transmission electron microscopy micrographs. In the following, a dispersive solid phase extraction (DSPE) method was developed using the synthesized CoCeFe ternary LDH as a sorbent for extracting perfluorooctanesulfonic acid (PFOS) from wastewater samples. For the selective analysis of PFOS, high-performance liquid chromatography-tandem mass spectroscopy (HPLC-MS/MS) in multiple reaction monitoring mode was used. Analytical parameters such as the limit of detection equal to 0.02 μg/L, with a linear range of 0.05–300 μg/L, the limit of quantification equal to 0.05 μg/L, and an enrichment factor equal to 23.3 were achieved for PFOS at the optimized condition (sorbent: 5 mg of CoCeFe ternary LDH, eluent type and volume: 150 μL mobile phase, pH: 3, adsorption time: 3 min, and desorption time: 5 min). The developed strategy for the analysis of PFOS was tested in real wastewater samples, including copper mine and petrochemical wastewater. The amount of analytes in real samples was calculated using the standard addition method, and good relative recovery in the range of 86%–105% was obtained. The main novelty of this research is the application of CoCeFe ternary LDH to extract the PFOS from wastewater using the DSPE method for determination by HPLC-MS/MS.

Bioactive Layered Double Hydroxides for Synergistic Sonodynamic/Cuproptosis Anticancer Therapy with Elicitation of the Immune Response.

Sonodynamic therapy (SDT) has promising application prospects in tumor therapy. However, SDT does not eradicate metastatic tumors. Herein, Cu-substituted ZnAl ternary layered double hydroxide nanosheets (ZCA NSs) were developed as both sonosensitizers and copper nanocarriers for synergistic SDT/cuproptosis cancer therapy. An optimized electronic structure more conducive to the sonodynamic process was obtained from ZCA NSs via the Jahn-Teller effect induced by the introduction of Cu2+, and the synthesized ZCA NSs regulated the intricate tumor microenvironment (TME) by depleting endogenous glutathione (GSH) to amplify oxidative stress for further enhanced SDT performance. Furthermore, cuproptosis was evoked by intracellular overload of Cu2+ and amplified by SDT, leading to irreversible proteotoxicity. In vitro results showed that such synergetic SDT/cuproptosis triggered immunogenic cell death (ICD) and promoted the maturation of dendritic cells (DCs). Furthermore, the as-synthesized ZCA NS-mediated SDT/cuproptosis thoroughly eradicated the in vivo solid tumors and simultaneously elicited antitumor immunity to suppress lung and liver metastasis. Overall, this work established a nanoplatform for synergistic SDT/cuproptosis with a satisfactory antitumor immunity.

Construction of porous flower-like Ru-doped CoNiFe layered double hydroxide for supercapacitors and oxygen evolution reaction catalysts

In recent years, ternary layered double hydroxide (LDH) has become a research hotspot for electrode materials and oxygen evolution reaction (OER) catalyst due to the enhanced synergistic effect between individual elements. However, the application of LDH is greatly limited by its low electrical conductivity and the disadvantage that nanosheets tend to accumulate and mask the active sites. Herein, a novel Ru-doped CoNiFe − LDH was prepared via a facile hydrothermal method. According to the density functional theory (DFT) calculations, the doping of Ru element could improve electron state density and band gaps of LDH and consequently boosted the electrochemical reaction kinetics as well as electrical conductivity. Furthermore, introduction of Ru atom induced the formation of porous flower-like structures in nanosheets. Compared to CoNiFe − LDH (28.9 m2/g), Ru-doped CoNiFe − LDH performed larger specific surface area of 53.1 m2/g, resulting in more electrochemically active sites. In these case, Ru-doped CoNiFe − LDH demonstrated better energy storage performance of 176.0 mAh/g at 1 A/g compared to original CoNiFe − LDH (78.9 mAh/g at 1 A/g). Besides, the assembled Ru-doped CoNiFe − LDH//activated carbon (AC) device delivered a maximum energy density of 36.4 W h kg−1 at the power density of 740.3 W kg−1 and an outstanding cycle life (78.7 % after 10,000 cycles). Meanwhile, Ru-doped CoNiFe − LDH exhibited lower overpotential (339 mV at 50 mA cm−2) and Tafel slope (93.2 mV dec−1). Therefore, this work provided novel and valuable insights into the rational doping of Ru elements for the controlled synthesis of supercapacitor electrode materials and OER catalysts.

Carbon supported ternary layered double hydroxide nanocomposite for Fluoxetine removal and subsequent utilization of spent adsorbent as antidepressant

Fluoxetine (FLX) is one of the most persistent pharmaceuticals found in wastewater due to increased use of antidepressant drugs in recent decades. In this study, a nanocomposite of ternary ZnCoAl layered double hydroxide supported on activated carbon (LAC) was used as an adsorbent for FLX in wastewater effluents. The nanocomposite was characterized using Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and surface area analysis (BET). The adsorption investigations showed that the maximum removal capacity was achieved at pH 10, with a 0.1 g/L adsorbent dose, 50 mL volume of solution, and at a temperature of 25 °C. The FLX adsorption process followed the Langmuir–Freundlich model with a maximum adsorption capacity of 450.92 mg/g at FLX concentration of 50 µg/mL. Density functional theory (DFT) computations were used to study the adsorption mechanism of FLX and its protonated species. The safety and toxicity of the nanocomposite formed from the adsorption of FLX onto LAC (FLX-LAC) was investigated in male albino rats. Acute toxicity was evaluated using probit analysis after 2, 6, and 24 h to determine LD50 and LD100 values in a rat model. The FLX-LAC (20 mg/kg) significantly increased and lengthened the sleep time of the rats, which is important, especially with commonly used antidepressants, compared to the pure standard FLX (7 mg/kg), regular thiopental sodium medicine (30 mg/kg), and LAC alone (9 mg/kg). This study demonstrated the safety and longer sleeping duration in insomniac patients after single-dose therapy with FLX-LAC. Selective serotonin reuptake inhibitors (SSRIs) like FLX were found to have decreased side effects and were considered the first-line mood disorder therapies.

High Entropy Induced γ-NiOOH Formation in Layered Double Hydroxide as Highly-Active and Ultra-Stable Electrocatalyst for Oxygen Evolution Reaction

Developing a low-cost and highly efficient oxygen evolution reaction (OER) electrocatalyst and understanding the underlying reaction mechanism are critical for sustainable renewable energy conversion and storage. In this study, high entropy layered double hydroxide (LDH) was self-supported on nickel foam using a simple hydrothermal method. The resulting binder-free high entropy LDH consisting of five different transition metals of Fe, Ni, Co, Mn, and Cr exhibits an excellent OER activity in alkaline condition with a low overpotential of 218 mV at a current density of 50 mA cm-2. It is superior to the binary, ternary, and quaternary-metal LDH counterparts. We demonstrate that the high entropy LDH possesses ultra-stable electrochemical stability at a high current density of 400 mA cm-2 for 600 h. The modulation of electronic structure facilitates the formation of the highly active γ-NiOOH and the shifting of the d-band center, resulting the outstanding OER performance. The excellent catalytic activity and stability of the high entropy LHD make it is as a highly potential candidate for commercial use.

Self-supporting trimetallic NiCoFe layered-double-hydroxide/amorphous sulfide heterostructure on nickel foam for efficient water splitting

For efficient overall water splitting, a ternary layered double hydroxide (LDH) and sulfide (NiCoFeLDH/NiCoFeS) composite on nickel foam (NF) has been developed as a bifunctional catalytic electrode. The growth of NiCoFeLDH/NiCoFeS–NF catalysts take place employing a three-step process that involves hydrothermal-sulfurization-hydrothermal reaction. Ultrafine nano-needle NiCo(OH)2 is deposited on the NF using a hydrothermal process, followed by immersion in Na2S solution, which ensures its mild conversion to NiCo sulfide. The Fe ions incorporated during the secondary hydrothermal process participate in the dissolution-recrystallization process of the lattice and modify the electronic structure, thereby significantly enhancing endogenous activity. The hetero-structured interface between NiCoFeLDH and NiCoFeS provides additional catalytic reaction sites, improves electronic interactions, and facilitates water dissociation kinetics. NiCoFeLDH/NiCoFeS–NF demonstates improved performance in both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The HER and OER overpotentials are measured to be only 191 and 241 mV at a current density of 100 mA cm−2 in 1 M KOH solution, respectively. Therefore, when NiCoFeLDH/NiCoFeS–NF has been employed as bifunctional electrodes for water splitting, 50 mA cm−2 is reached at only 1.63 V.

Flower-like FeCoNi ternary composite formed by interweaving nano needles for positive electrode material of supercapacitor

Ternary layered double hydroxide (LDH) are potential electrode material choices for supercapacitors (SCs) due to their various oxidation states and high theoretical specific capacitance. In this paper, FeCoNi-LDH composite with cross-braided flowers of nanoneedles has been prepared by a single-step hydrothermal method. By highlighting the structural and morphological advantages, the obtained ternary LDH shows lower resistivity in comparison with the binary LDH. As electrode material, the ternary LDH exhibits excellent electrochemical properties, such as superb specific capacitance of 2163.3 F·g−1 at 0.5 A·g−1 and good cycle retention rate of 93.8% after 5000 cycles at 20 A·g−1. Meanwhile, the assembled asymmetric flexible solid-state supercapacitor device can provide 44.8 Wh·kg−1 energy density at 807.5 W·kg−1. Moreover, two devices in series can also light up miniature light bulbs of different hues and maintain them for a long period when they are connected in series.

Phase‐Bridged Hierarchical Catalysts for Efficient and Stable Water Electrolysis

AbstractThe design and synthesis of low‐cost electrocatalysts with high catalytic activity and long‐term stability is a challenging task. This study utilizes a combination of electronic tuning and surface reconstruction to synthesize a ternary layered double hydroxide (LDH)/phosphide (P−NiCuFe−LDH) hierarchical‐structure catalyst that improves the kinetics of the hydrogen/oxygen evolution reactions in water electrolysis by facilitating the thermodynamically limited reaction pathways. Spectroscopic analyses indicate synergistic electronic interactions among the metal atoms in the LDH and phosphide layers via the P‐bridge effect. This cross‐layer interaction optimizes the electron transport pathways and reaction kinetics, enabling the proposed hierarchical electrocatalyst to exhibit high intrinsic activity. Theoretical calculations confirm the configuration of the cross‐phase bridges and elucidate the origin of the enhanced electrocatalytic effect of P−NiCuFe−LDH. For overall water splitting, the P−NiCuFe0.06−LDH || P−NiCuFe0.06−LDH system requires only 1.517 V to attain a current density of 10 mA cm−2. The P−O‐containing surface (generated in situ during water electrolysis) prevents metal‐ion leaching and endows P−NiCuFe−LDH with excellent operational stability; as demonstrated by the continuous long‐term stability test over 1000 h with negligible performance degradation. This study provides important insights into the design of rational hierarchical structures for a wide range of applications beyond water splitting.

Ag-Coated Ternary Layered Double Hydroxide as a High-Performance SERS Sensor for Aldehydes.

Volatile organic compounds (VOCs) are common environmental pollutants and important biomarkers for early diagnosis of lung cancer. However, aldehydes are difficult to detect directly due to their small Raman scattering cross-section and gaseous phase. Here, a Ag-coated ternary layered double hydroxide (LDH) was designed for the detection and identification of various aldehydes. The specific surface area of CoNi-LDH was increased by doping Fe3+, which provides abundant active sites to capture gas molecules. Furthermore, the energy band gap (Eg) was decreased due to the local amorphous FeCoNi-LDH with an extended band tail, promoting the excitonic transition of Fe0.07(CoNi)0.93-LDH. In addition, the Fermi level of Ag prevented the recombination of electron-hole pairs of Fe0.07(CoNi)0.93-LDH, providing a new bridge for charge transfer between the substrate and the molecule. Ag/Fe0.07(CoNi)0.93-LDH presented excellent surface-enhanced Raman scattering (SERS) performance for aldehyde VOCs by modification with 4-aminothiophenol (4-ATP) to capture aldehydes and realized the detection of benzaldehyde (BZA) at 10 ppb. The enhancement and Raman shift of the b2 mode indicated the contribution of chemical enhancement to the SERS system, so the substrate presented good uniformity. The recycling of the SERS substrate is realized based on the reversibility of the Schiff base reaction. These results manifested that Ag/FeCoNi-LDH has a wide prospect in the application in the trace detection of aldehydes.

Montmorillonite modified Ni/Mg/Al ternary layered double hydroxide nanoflowers with enhanced adsorption features

A hydrothermal technique was employed to synthesize Ni/Mg/Al ternary L.D.H.s modified with montmorillonite (NMA-MMT-LDHs). Many characterization methods, including X-ray diffraction (XRD), scanning electron microscopy (S.E.M.), Fourier transform infrared (FTIR), and Brunauer, Emmett, and Teller (B.E.T.), were used to assess the physiochemical properties of the produced analytes. Congo red and methylene blue were utilized as model dyes to treat textile waste with the synthesized analytes. The batch adsorption model was utilized to conduct the adsorption experiments under varying contact time, adsorbent dosage, and solution pH conditions. A pseudo-second-order kinetics and the Langmuir adsorption model control the adsorption process. The maximum monolayer adsorption capacities of C.R. and M.B. were determined to be 344 and 200 mg/g, respectively. As the quantity of dosage increased from the 0.01–0.04 g, the percent removal efficiency (%) increased from 75 to 87 % for S2-LDH, 84–88 % for S2-MMT, 86–93 % for S3-MMT, and 95–97% for S4-MMT for C.R. dye and 82–85 % for S2-LDH, 83–89 % for S2-MMT, 83–91 % for S3-MMT, and 84–92 % for S4-MMT for M.B. dye. The removal percentage of C.R. dye for adsorbents S2-LDH, S2-MMT, S3-MMT, and S4-MMT were 75 %, 84 %, 86 %, and 95 %, respectively and 82 %, 83 %, 83 %, and 85 %, respectively for the M.B. dye removal. The presence of MMT significantly increases the affinity of Ni/Mg/Al-LDHs (NMA-LDHs), and the designed production technique can be used to produce a variety of compositionally distinct adsorbent materials.

012 facets modulated LDH composite for neurotoxicity risk assessment through direct electrochemical profiling of dopamine

Rising concerns of pesticide-induced neurotoxicity and neurodegenerative diseases like Parkinson's, Alzheimer's, and Multiple Sclerosis, are exacerbated by overexposure to contaminated waterbodies. Therefore, evaluating the risk accurately requires reliable monitoring of related biomarkers like dopamine (DA) through electrochemical detection. Layered double hydroxides (LDHs) have shown great potential in sensors. However, to meet the challenges of rapid detection of large patient cohorts in real-time biological media, they should be further tailored to display superior analytical readouts. Herein, a ternary LDH (Ni2CoMn0.5) was integrated with the sheets of thermally reduced graphene oxide (trGO), to expose more highly active edge planes of the LDH, as opposed to its generally observed inert basal planes. The improvement in detection performance through such a modulated structure-property is a prospect that hasn't been previously explored for any other LDH-based materials employed in sensing applications. The 2 folds superior electrochemical activity exhibited by the face-on oriented LDH with trGO as compared to the pristine LDH material was further employed for direct detection of DA in real blood plasma samples. Moreover, the designed sensor exhibited exceptional selectivity towards the detection of DA with a limit of detection of 34.6 nM for a wide dynamic range of 0.001–5 mM with exceptional stability retaining 88.56% of the initial current even after storage in ambient conditions for 30 days.

(Cu3-x Nix)Co2-Layered Double Hydroxide Nanosheets for Enhanced Electrocatalytic Activity Towards Overall Water Splitting

The exploration of transition metal based electrocatalyst for overall water splitting is becoming important as hydrogen becomes integral part of energy landscape. Recently, a new class of compounds i.e. layered double-hydroxides (LDHs), also known as anionic clays, are have shown tremendous promise for use as electrocatalyst. The lamellar morphology of LDHs accommodates higher active sites, that contributes to the facile electron transfer and thus attracts a great deal of interest in catalysis application. Moreover, the high catalytic activity of LDHs are also linked to their facile anion exchange, specific electronic structures, and versatile chemical compositions.Herein, we have developed a series of ternary layered double hydroxide (LDH) using pH-adjusted co-precipitation method with varying ratio of Cu, Ni and Co, which are used as an electrocatalyst for overall water splitting. (CuxNi1)Co1-LDHs (x = 0.5 1, 1.5, and 2 ) were systematically characterized using XRD, XPS, SEM, FTIR, TEM and BET techniques. The synergistic contributions from the electrocatalytically active metals and lamellar morphology of LDHs promotes water dissociation, facilitates faster release of H2-O2 gas bubbles, ameliorate electrolyte ion diffusion and improves electron transfer rate. It is further observed that the (CuxNi1)Co1-LDHs showed excellent electrocatalytic activity for both hydrogen evolution (HER) and oxygen evolution reaction (OER) with an overpotential of 147 and 218 mV for HER and OER, respectively at 10 mA cm-2. Tafel slope was found to be lowest for (Cu1Ni1)Co1-LDH. Further, the durability of the materials was also analysed by performing chronoamperometry for over 12 h. The overall water electrolytic cell using (Cu1Ni1)Co1-LDH as both electrodes can reach 50 mA cm−2 at 1.9V with outstanding durability.

Heterogeneous activation of permonosulfate by biochar supporting CuCoFe layered double hydroxide for rapid degradation of phenanthrene

In this study, a ternary layered double hydroxide (CuCoFe-LDH) coated on corn straw-based biochar (BC@LDH) was synthesized and characterized using various approaches. Application in heterogeneous activation of permonosulfate (PMS) for the degradation of phenanthrene (PHE) suggested that the higher Co content in the material, the higher the catalytic activity, maximum of which was 96.5% reached at catalytic dosage of 0.2 g/L, PMS concentration of 2.0 mmol/L, pH 7 and temperature of 45 ℃ within 15 min in BC1 @LDH1 (BC to mass ratio of 1:1)/PMS system. Improved PHE degradation and wide pH application range supported that BC not only acted as CuCoFe-LDH carrier, but also probably participated in the activation of PMS due to abundant functional groups, like hydroxyl as FT-IR revealed. Co-existing ions (NO3-, CO32-) and humic acid (HA), but not Cl-, significantly inhibited PHE degradation. Moreover，the removal of PHE was mainly attributed to SO4·- and ·OH, while O2·− and 1O2 contributed less. It was proposed that Cu (I), Co (II) and Fe (II) were responsible for the PMS activation and produced Co (III) can be reduced by HSO5- and Fe (II) to achieve Cu (I)/Co (III) cycle, thereby maintaining high catalytic activity and structural stability of BC1 @LDH1. Remarkably, Consecutive runs (>80.0% PHE removal after 4 cycles) and low level of leaching metal concentration (0.053 mg/L of Co and 0.077 mg/L of Cu at pH 7) all implied that BC1 @LDH1 possesses much greater potential in activating PMS for practical application.

Preparation of FeCoM Ternary Layered Double Hydroxides

LDHs have unique laminar structures, large interlaminar spacing ions, and highly adjustable components, which have been widely used in the field of electrochemistry. However, it is still a considerable challenge to regulate the microstructure and electronic structure of LDHs through reasonable design to obtain electrode materials with high activity. In this paper, three novel ternary-layered dihydroxide nano-compounds have been synthesized. Firstly, three LDHs materials (named as FeCoNi-LDHs, FeCoCu-LDHs, and FeCoZn-LDHs, respectively) were prepared by using the ZIF-67 framework material as a precursor by cation exchange strategy. Finally, the applications of these materials as electrode materials in oxygen evolution reactions (OER) and supercapacitors are explored based on current energy problems.

Ternary MnFeZn layered double hydroxides as an efficient material for the electrochemical sensing of flutamide

Layered double hydroxides (LDHs) have been gaining interest in electrochemical sensors due to their ease of making and significant performances. In this work, we have developed a simple and low-cost method for the preparation of ternary LDH. The MnFeZn-LDH was prepared and initially characterized to explore its formation. Further, the glassy carbon electrode (GCE) modified with MnFeZn-LDH was employed for the electrochemical analysis of flutamide (FLA). Thus, the prepared ternary MnFeZn-LDH was prominent with better sensitivity of about 5.04 μAμM−1 cm−2 and selective over several interferants injected over the MnFeZn-LDH fabricated electrode. The limit of detection was appreciable with a linear range of 0.019–2735.79 µM about 12.9 nM. Also, other technical analyses showed good electrochemical performances as a higher rate of repeatability and reproducibility. The stability of the electrode was retained for 50 cycles and the real sample detection in river water showed significant potentiality. Thus, the as-described work evolves the better enhancement with MnFeZn-LDH towards FLA detection. The better electrocatalytic properties of the prepared LDH paves the way for its exploration in various application.

Phosphorous recovery from water via batch adsorption enrichment combined with struvite crystallization in a fluidized bed reactor

To assess the feasibility of recovering P from water by combining batch adsorption enrichment with struvite crystallization, we prepared four ternary layered double hydroxides (LDHs) with P-preferring elements (i.e., zirconium (Zr) or lanthanum (La)) via a facile coprecipitation method, and evaluated their performance in recovering P from water, particularly in enriching P from a low-level P solution. We find that all ternary LDHs demonstrate remarkably high P adsorption capacities, e.g., 1029.3 mg PO43− g−1 for ZnAlLa, outperforming other LDHs reported so far. Microstructural analyses show that the P uptake mechanisms are attributable to anion exchange, surface complexation and electrostatic attraction. Results of recycling tests indicate that all LDHs present good enrichment for P. Besides, more than 96% of phosphorus in the P-enriched eluates can be efficiently reclaimed via struvite crystallization in a fluidized bed reactor. These findings demonstrate the feasibility of combining adsorption enrichment with struvite crystallization for P recovery.

Hybrid ternary NiCoCu layered double hydroxide electrocatalyst for alkaline hydrogen and oxygen evolution reaction

This study focuses on the electrochemical properties of layered double hydroxide (LDH), which is a specific structure of NiCoCu LDH, and the active species therein, rather than the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) of ternary NiCoCu LDH materials. Six types of catalysts were synthesized using the reflux condenser method and coated onto a nickel foam support electrode. Compared to bare, binary, and ternary electrocatalysts, the NiCoCu LDH electrocatalyst exhibited higher stability. The double layer capacitance (Cdl) of the NiCoCu LDH (12.3 mF cm−2) is greater than that of the bare and binary electrocatalysts, indicating that the NiCoCu LDH electrocatalyst has a larger electrochemical active surface area. In addition, the NiCoCu LDH electrocatalyst has a lower overpotential of 87 mV and 224 mV for the HER and OER, respectively, indicating its excellent activity with the bare and binary electrocatalysts. Finally, it is demonstrated that the structural characteristics of the NiCoCu LDH contribute to its excellent stability in long-term HER and OER tests.

High entropy promoted active site in layered double hydroxide for ultra-stable oxygen evolution reaction electrocatalyst

In this study, high entropy layered double hydroxide (LDH) grown on nickel foam using a simple hydrothermal method is reported. The high entropy LDH consisting of five different non-noble transition metals of Fe, Ni, Co, Mn, and Cr (denoted as FeNiCoMnCr) exhibits an excellent OER activity in alkaline condition with a low overpotential of 218 mV at a current density of 50 mA cm−2. It is superior to the binary, ternary, and quaternary-metal LDHs. We demonstrate that the high entropy FeNiCoMnCr LDH possesses ultra-stable electrochemical stability at a high current density of 400 mA cm−2 for 600 h, which is the best stability of all the reported high entropy material electrocatalysts so far. The interaction among the multi-metal components along with the resulting electronic structure modulation facilitates the formation of highly-active γ-NiOOH species, significantly boosting catalytic activity; while the high entropy induced phase stability contributes to the superior durability.

Electrosynthesized CuMgAl Layered Double Hydroxides as New Catalysts for the Electrochemical Reduction of CO2

AbstractIn this study, new nanostructured CuMgAl Layered Double Hydroxide (LDH) based materials are synthesized on a 4 cm2 sized carbonaceous gas diffusion membrane. By means of microscopic and spectroscopic techniques, the catalysts are thoroughly investigated, revealing the presence of several species within the same material. By a one‐step, reproducible potentiodynamic deposition it is possible to obtain a composite with an intimate contact between a ternary CuMgAl LDH and Cu0/Cu2O species. The catalyst compositions are investigated by varying: the molar ratio between the total amount of bivalent cations and Al3+, the amount of loading, and the molar ratios among the three cations in the electrolyte. Each electrocatalyst has been evaluated based on the catalytic performances toward the electrochemical CO2 reduction to CH3COOH at −0.4 V versus reversible hydrogen electrode in liquid phase. The optimized catalyst, that is, CuMgAl 2:1:1 LDH exhibits a productivity of 2.0 mmolCH3COOH gcat−1 h−1. This result shows the beneficial effects of combining a material like the LDHs, alkaline in nature, and thus with a great affinity to CO2, with Cu0/Cu+ species, which couples the increase of carbon sources availability at the electrode with a redox mediator capable to convert CO2 into a C2 product.

Comparative Study on Corrosion Resistance of Binary and Ternary Layered Double Hydroxide Films on Magnesium Lithium Alloy

Layered double hydroxide (LDH) (Mg-Al and Mg-Al-Co) films were prepared on the surface of LA103Z magnesium-lithium alloy by hydrothermal synthesis method. Corrosion resistance of binary and ternary LDH coatings was studied by comparison. Structures of the two films were characterized using XRD, FTIR, SEM and EDS, and the corrosion resistance of the films was evaluated by polarization curve, EIS, and hydrogen evolution rate during immersion in 3.5 wt% NaCl solution. Results showed that Mg-Al LDH film was tightly bonded to the substrate and had a large number of nanosheets growing perpendicular to the substrate, while Mg-Al-Co LDH film was thinner with a smaller size and fewer nanosheets. Electrochemical test results showed that the polarization resistance of Mg-Al and Mg-Al-Co LDH films was two orders of magnitude higher than that of the substrate. Hydrogen precipitation experiments showed that corrosion resistance of both the films was improved compared to the substrate, and the films played a protective role for the substrate, among which the corrosion resistance of the Mg-Al LDH layer was better than that of the Mg-Al-Co LDH layer.